This invention pertains to flow control valves used down hole on drill strings to exercise down hole main stream valve control from the surface. More specifically, it pertains to valves controlled by manipulation of the flow rate of fluid pumped down the drill string bore.
Apparatus of U.S. Pat. No. 6,167,969 is preferred for used in the preferred embodiment of this invention. U.S. Pat. 6,167,969 is, by reference herein, made part of this application.
During the drilling, completion work, and servicing of wells it is necessary to use the flow of fluid moving down the drill string bore to accomplish tasks outside the drill string. Washing down the casing inside walls before conducting some planned activities is an example. The washing down process requires the full flow of the available fluid stream.
In the past, several devices made possible the control of the down hole valves by actions carried out at the surface. Balls, darts, and spears were dropped down the drill string bore. Very often the drill string had to be tripped to make further changes in the down hole assembly to convert back to the usual drilling activity.
In a housing arranged to serve as a length element of the drill string a selector control valve is situated with a controlling element to be moved to the extent of it""s limited travel by entrainment with the moving fluid in the drill string bore. The valve entrained element is the poppet situated to cooperate with an orifice in the flow path. In the preferred embodiment, on alternate downward excursions of the poppet, the poppet is allowed to move down to engage the orifice, and to move a selected distance with the orifice. On other downward excursions, the poppet is stopped well above the orifice, and the flow is not significantly impeded.
The orifice is carried by a piston that actuates a by-pass valve. The closed orifice creates enough differential pressure to move the piston until the piston opens enough by-pass area to accommodate the flow in the drill string bore. In the preferred embodiment, the piston is the movable element of a valve that opens to direct the fluid flow in the drill string bore through openings in the housing wall.
When fluid flow down the drill string bore is reduced below a selected amount, a spring urges the piston to close the by-pass valve. A spring in the selector valve urges the entrained poppet to return to the starting, and open, position. On the return trip, the selector valve actuator carrying the entrained element actuates a walk-around turret, well known in the art, to pre-set the actuator for a limited downward trek on the next onset of fluid flow which does not operate the by-pass valve.
While the by-pass valve is not actuated, fluid flow in the drill string bore proceeds down the flow channel as if no by-pass valve existed. A subsequent cessation of fluid flow presets the actuator walk-around to actuate the by-pass valve on the subsequent onset of fluid flow.
Each start and stop cycle of fluid flow actuates the walk-around to change the fluid flow path that follows the next onset of fluid flow.
The selector valve described above is a preferred embodiment because it exists in proven and reliable form. The by-pass valve will respond to any selector valve capable of occluding the fluid flow through the described orifice. It will respond to an object dropped down the drill string bore to occlude the orifice. Recovery of the object by wire line is an activity used in the past.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.